The goal of the program is to identify the key metabolic pathways/reactions and regulatory transcription factors that are associated with M. tuberculosis growth arrest (a physiological state related to persistent infection). Preliminary study by transcription profiling of M. tuberculosis carbon metabolism in a murine model of persistent infection led to a hypothesis that a coordinated metabolic transformation occurs during the establishment of persistent state. It represents a drastic different carbon flow patterns in growing and growth-arrested bacilli. While carbons are utilized for energy generation and biosynthetic precursors for bacterial growth in growing cells;in persistent cells carbons are mainly mobilized for the formation of storage compounds. To test the hypothesis, 13C isotope-labeling experiment in combination with metabolic network modeling will be used to determine carbon flows among various pathways/reactions by measuring isotopomer distribution to their precursor metabolites in growing and nongrowing steady-state cultures. This approach will allow the identification key metabolic pathways/reactions associated with bacterial persistence. Second, reporter fusion and transposon mutagenesis technology will be utilized to study whether key metabolic genes are regulated in a coordinated mode. This approach will lead to identification of transcription factors that regulate key metabolic genes during persistence. This program is expected to provide new insights into the persistent mechanism of tubercle bacilli and offer possible strategies to tackle the persistent infection. PUBLIC HEALTH RELEVANCE: The goal of the program is to identify the key metabolic and regulatory events during the establishment of M. tuberculosis persistent infection. The program is expected to lead to new knowledge about the persistent mechanism of the tubercle bacilli and offer new strategies to tackle the persistent infection.